1. Field
The present disclosure relates generally to communication systems, and more particularly, to avoiding collisions.
2. Background
In order to address the issue of increasing bandwidth requirements that are demanded for wireless communications systems, different schemes are being developed to allow multiple user terminals to communicate by sharing the channel resources while achieving high data throughputs. Different wireless technologies have been adopted in several emerging wireless communications standards such as the Institute of Electrical Engineers (IEEE) 802.11 standard. IEEE 802.11 denotes a set of Wireless Local Area Network (WLAN) air interface standards developed by the IEEE 802.11 committee for short-range communications (e.g., tens of meters to a few hundred meters), for example, 802.11 ad/ac/a/b/g/n/z.
Generally, wireless communications systems specified by the IEEE 802.11 standard have a central entity, such as an access point (AP) that manages communications between different devices, also called stations (STAs). Having a central entity may simplify design of communication protocols. Further, although any device capable of transmitting a beacon signal may serve as an AP, for an AP to be effective it may have to have a good link quality to all STAs in a network.
Mobile wireless communications devices (WCD) (e.g., laptops, smartphones, STAs, etc.) may have comparatively reduced capabilities to that of a traditional AP due to factors such as cost, power, form factor, etc. For example, antenna steering capability may be limited to a small sector bound, available power may be limited, location may be variable, etc. Even with these limitations, WCDs may be asked to perform as APs to form peer-to-peer networks for various purposes, such as side-loading, file sharing, etc.
In some aspects, it is desired to improve communications between WLAN STAs. For example, 802.11z defines a power save mechanism in which two STAs are awake at scheduled time periods, referred to as Awake Windows. The power save mechanism is referred to as Peer Power Save Mode (Peer PSM). It is possible, however, for each STA to attempt to transmit a frame to the other STA at the start of the Awake Window. Such an attempt may cause a collision. Therefore, improved collision avoidance protocols may be beneficial so as to not overly penalizing STAs by mandating that they start a backoff at the start of each Awake Window.